John is buying floor tile to put in a room that is 10 ft by 15 ft. He has chosen tiles that are 18 in by 18 in. Assuming that he needs to buy 10% extra to be safe, how many tiles would he need to buy.

I know that I need to buy enough for 150 square feet, but I'm not sure what my next step would be since that is in square feet and my tiles are in inches.

3 answers

10/1.5 = 6.67 tiles
15/1.5 = 10 tiles

6.67 * 10 = 66.7

66.7 * 1.1 = 73.37 = 74 tiles
What does the 1.5 represent that you divided by?
18 inches = 1.5 feet